Information is commonly received from innumerable databases over computer networks such as the Internet by using one or more well known search engines or query servers such as the Google® search engine by Google, Inc. of Mountain View Calif. Search engines generally employ various systems and algorithms in response to a user query having one or more search terms to generate a hit list of documents including relevant instances of the search terms. The hit list typically includes uniform resource locaters (URLs), (i.e., web addresses) of the found documents.
A typical search engine uses a proprietary index associating every word in the documents being searched with a URL or pointer to the document in which the word is found. The proprietary index is automatically generated with a web crawler. In an illustrative search for a document in response to a query having a plurality of search terms, a search engine first accesses the index to generate a list of URLs associated with a first search term then narrows the list of URLs by successively searching for members of the list which are also associated with a second search term in the index, etc.
Search engines have also been employed to control access codes associated with the documents. For example, a search engine may maintain a list of users and their corresponding access code or credentials. Before providing a hit list to a user, the search engine checks the requester's access code on the list and removes from the hit list any URLs for documents for which the requester's access code does not meet the document's authorized access code.
Previously known search engines have maintained the user access code list on a query server or, with improved efficiencies, on a local web server, as in U.S. Pat. No. 7,031,954. Only after the processing involved in generating a hit list is complete, however, do such search engines compare access codes of found documents with searcher's access code. The generation of a preliminary hit list including documents which can not be delivered to the searcher or included on a delivered hit list can be wasteful of processing and storage resources.